Danish mobile game company Kiloo’s free-to-play mobile title Subway Surfers is putting up powerful numbers. With 26.5 million daily active users, 130 million downloads, and a projection for 250 million downloads in 2013, Subway Surfers is making some waves. At the core are impressive user retention rates as well - Day 1: 91% Day 7: 81% Day 30: 60% So how do they do it?